Crazy Scheme: Fully charged 12v runs at, what, 12.6, 13v?

EYDavis · Apr 1, 2013

Why not run, say 2x12v's or 3x6v batteries in series with a voltage regulator set to 12.6v or 13v or whatever? Wouldn't that have the effect of running the TM at a "fully charged" max voltage for longer? I know I could run two 12's in parallel, like a "permanent jump" and have more capacity (I know, identical batteries, etc. etc.), but it seems as though as long as I could find a voltage regulator/limiter, that the defacto 24v or 18v sure would take a long time to run down.

I actually took an e-mag physics course in college, but it's fuzzy. 20 years ago. I know there are amperage questions here, too....which is the reason I can't just take a bunch of 9volts from the grocery store checkout line. What's specifically got me interested is the idea of "sealing off" some AGM's under a bench for low-maintenance power, high thrust, long lasting power.

And, yes, I have an electric-only lake or two in mind. And I just bought a Kipawa for my Minn Kota 45 thrust. And I just spent 7 hours on Saturday with a Wal-Mart deep cycle running my MK 45 with only a tiny dip in perceived thrust at the end of the day. Could've gone a lot longer. But I like batting this kind of stuff around. I never "overclocked" a CPU on a computer, but I grasped the concept. This would be minimal overclocking....not like trying to run 24v straight through a 12v.

I had this idea watching my kid ride his (12v) john deere around, and noticing that it sure ran faster right off the charger. I'm sure it was pushing 13.9 volts or something early on. Then, as he went on through the day, it dragged. I suspect it bottomed out around 11 and some change.

Any experts on e-mag out there? Am I way off base? Should I shut up and go wire wheel my 1st tinboat so I can prime it? I guess I'm fired up about 'overclocking' a minn kota a little.

kofkorn · Apr 2, 2013

Logic here is sound, but the practice is a little more complicated.

1st off, a voltage regulator to handle the power needed by a trolling motor would be very large and need to dissipate a huge amount of heat. On top of that, the cost would be pretty high. See this: https://www.current-logic.com/shop/index.php?main_page=product_info&cPath=5&products_id=32

2nd, while it may make your motor run more consistently, you would actually get less use out of the batteries than if you had just wired them in parallel (Assuming 2-12v's) due to the 80-85% conversion factor. About 15-20% of your power would be lost to heat.

3rd, when you do this, you would have to keep a very close eye on your battery level, even to the point of having a logically controlled voltage cut-off. If not, you could easily run your batteries down to 30% and quickly kill the batteries without knowing it.

You'd be better off getting two good gel batteries, and a good trolling motor with a PWM control or Maximizer. This way you'll be using the batteries the most efficient way possible.

Or you could put it together for the giggles. Your choice

EYDavis · Apr 2, 2013

kofkorn said:
Logic here is sound, but the practice is a little more complicated.

You'd be better off getting two good gel batteries, and a good trolling motor with a PWM control or Maximizer. This way you'll be using the batteries the most efficient way possible.

Or you could put it together for the giggles. Your choice

Wondering about this Pwm or maximizer...googled enough to get real intimidated. Ran into something about Chinese scooter controllers and all of a sudden I was in way deep. Thanks for the reassurance that its not totally batty.

This pwm thing sounds interesting. What's a maximizer?

--edit-- gotcha. So on my MK endura c2 45 thrust I need to beware of overheating wires, but as long as I don't exceed 42 amps, I'm ok with the right Chinese scooter controller? Worried about the throttle, though.

JMichael · Apr 2, 2013

If you're wanting have a TM that's more efficient, I think your best option would be to sell your current TM and buy a more modern one with the features you're looking for. There's no need to reinvent the wheel when it's already out there. And not to knock your skills, but you'd probably end up with a better system if you purchased one rather than trying to re-purpose some scooter part that may or may not work for you. And it would probably be cheaper in the long run to buy the new TM.

EYDavis · Apr 3, 2013

JMichael said:
If you're wanting have a TM that's more efficient, I think your best option would be to sell your current TM and buy a more modern one with the features you're looking for. There's no need to reinvent the wheel when it's already out there. And not to knock your skills, but you'd probably end up with a better system if you purchased one rather than trying to re-purpose some scooter part that may or may not work for you. And it would probably be cheaper in the long run to buy the new TM.

Fair enough, but if I'm reading right, the right pwm would not only be more efficient, but also allow 24v in without frying it. And knock skills all day...I have no idea what I'm doing. Just trying to over clock a TM.

Just thought this was a fun read. https://www.cfnet.net/tm/

I did think this was interesting: * For this test two Voltmeters were connected, one at the MK control head switch, the other at the output of the scooter controller. ‘M Voltage’ on all non-controller tests was measured at the MK control head. ‘M Voltage’ on all scooter controller tests was as measured at the controllerrr. However, when it is 30A and 12V (or 14V) at the controller, it is 10V (or 12V) at the switch! There is a TREMENDOUS loss in the stock 14GA MK Battery Connection wire at 30A.Therefore, the least expensive way to get more performance from your 30/34 MK at 30A is to replace the Battery wire AT THE SWITCH with 10GA or heavier.

kofkorn · Apr 3, 2013

The PWM controller won't likely make any adjustments to the voltage coming in. It simply is a very high speed on/off switch (~100 cycles /sec). By controlling the amount of "on" time vs "off" time at a very high speed, it is able to control the speed of the motor.

Take a look at this thread where I used a PWM controller on a couple of my TM's:
https://www.tinboats.net/forum/viewtopic.php?t=26975&p=277661#p277657

Now because the PWM is simply a fast switch, it doesn't change the voltage. What comes in goes out. But it is more efficient that the standard speed coils because it's not dumping extra electricity to slow the motor down. With speed coils, the TM is running the least efficiently when it is on the lowest speed. And since most of your TM use is in the lower speeds, adding the PWM will give you more battery life.

You might be able to find a PWM with a wide input range, but I'm not aware of any that do voltage conversion in addition to the PWM logic.

If you want to play, go ahead with the Chinese Scooter controller. Make sure to put a circuit breaker in-line first. But understand that if you don't hook things up properly, you could be looking for a new motor too.

I've always had fun putting things together on the cheap. I got an old Power Drive with a bad speed switch off of Craigslist for $25 and the PWM electric controller cost me $25. So for $50 I ended up with a perfectly working Power Drive motor with a PWM controller. Looking at the new ones around $500, I think I got a pretty good deal.

Good Luck!